The NVR displays a gray screen

ONVIF is the protocol used by the NVR to control the camera.

The gray screen is caused by the NVR incorrectly configuring the program’s video encoder:
– the bit rate is too low; the Video encoder/H.264 configuration/Bitrate limit parameter should be greater than 100 kbps;
– low compression quality; the Video encoder/Compression Quality parameter should be greater than 20%.

With such compression parameters, the image is heavily compressed and degenerates into a few gray pixels—a gray spot.

Two possible fixes:
– correctly configure these parameters in the NVR;
– prevent the NVR from changing the program’s settings: to do this, create a user with Operator rights in the program and register the program in the DVR with this user.